As the majestic planet Saturn approaches opposition on March 21st, I’d like to turn your telescopic attention to one of the most bizarre moons in the solar system; Iapetus. It was way back when in the 17th century that Italian astronomer Giovanni Cassini noted that he could only see Iapetus when it was to the west of the ringed planet, but never to the east. He correctly deduced that Iapetus must not only be tidally locked, that is, holding one face towards Saturn, but must be correspondingly dark on one hemisphere and brighter on the other. In fact, Iapetus is known to vary from magnitude +10 to magnitude +12 over its 79 day orbit, a variation of 6 times in terms of brightness. the Cassini space probe has confirmed the duality of Iapetus, showing us a dark leading hemisphere with an albedo of 5% (think fresh asphalt) and a trailing hemisphere with an albedo of about 50% (think dirty snow). The third largest of the Saturnian moons, Iapetus is a “walnut shaped” world, with a large ridge running the equator of this twisted moon. Discovered by Cassini on New Year’s Eve 2004, no satisfactory explanation for the ridge is known, but the little world must have had a tumultuous history.

What is it? Earlier this week, the above image and obligatory YouTube video flew around ye ‘ole Internet, purportedly showing an “Independence Day”-like spacecraft seemingly descending through the clouds over Moscow. The video was shaky, and the perspective of the light poles moving in the foreground all lent themselves to an eerie look and feel…a classic UFO, right?

Semi-unfortunately, this phenomena has a slightly more prosaic explanation, although its still pretty cool. Many naysayers are simply claiming that the video was “Photo-shopped” although we here at Astroguyz HQ don’t necessarily believe so. The patterns look to be consistent with low altitude, mammatus-type clouds. Of course, the hoaxer might have been a meteorologist…what your looking at is known as a parahelic arc, a breed of sun-dog shining through low-altitude clouds seen under somewhat unusual conditions. Many folks on the ‘Net have stated that the glowing ring is the cloud, but if you look closely, the entire sky is overcast. Meteorologists confirm that a converging front was over Moscow at the time, and that the sun was indeed at a low angle, i.e. prime sun-dog conditions. To explore near-sky phenomena complete with explanations, I refer you to Les Cowley’s excellent site on Atmospheric Optics. Stare at the sky long enough, and you’ll see all sorts of bizarre things. Incidentally, pilots are much more familiar with this sort of reflection phenomenon, as they frequently fly above low cloud banks. I would suspect that there is also an inversion source, like say, a heat belching factory right below the halo. Alas, no ET…but isn’t UFO debunking fun?

Astro Documentaries

Pictured is a Delta IV rocket launch from Cape Canaveral on November 21st, 2010. The image is a 20 second exposure taken at dusk, shot from about 100 miles west of the launch site. The launch placed a classified payload in orbit for the United States Air Force.

DIY Astronomy

Difficult but not impossible to catch against the dawn or dusk sky, spotting an extreme crescent moon can be a challenge. The slender crescent pictured was shot 30 minutes before sunrise when the Moon was less than 20 hours away from New. A true feat of visual athletics to catch, a good pair of binoculars or a well aimed wide field telescopic view can help with the hunt.

The Sun is our nearest star, and goes through an 11-year cycle of activity. This image was taken via a properly filtered telescope, and shows the Sun as it appeared during its last maximum peak in 2003. This was during solar cycle #23, a period during which the Sun hurled several large flares Earthward. The next solar cycle is due to peak around 2013-14.

Astronomy Gear Reviews

Located in the belt of the constellation Orion, Messier 42, also known as the Orion Nebula is one of the finest deep sky objects in the northern hemisphere sky. Just visible as a faint smudge to the naked eye on a clear dark night, the Orion Nebula is a sure star party favorite, as it shows tendrils of gas contrasted with bright stars. M42 is a large stellar nursery, a star forming region about 1,000 light years distant.

Astronomical Observing Targets

Orbiting the planet in Low Earth Orbit (LEO) every 90 minutes, many people fail to realize that you can see the International Space Station (ISS) from most of the planet on a near-weekly basis. In fact, the ISS has been known to make up to four visible passes over the same location in one night. The image pictured is from the Fourth of July, 2011 and is a 20 second exposure of a bright ISS pass.

Next to the Sun, the two brightest objects in the sky are the Moon and the planet Venus. In fact, when Venus is favorably placed next to the Moon, it might just be possible to spot the two in the daytime. Another intriguing effect known as earthshine or ashen light is also seen in the image on the night side of the Moon; this is caused by sunlight reflected back off of the Earth towards our only satellite.

A mosaic of three images taken during the total lunar eclipse of December 21st, 2010. The eclipse occurred the same day as the winter solstice. The curve and size of the Earth’s shadow is apparent in the image.